Sex Chromosome Conditions: Terminology

Correct Answer: All correctly matched

From the notes:

• XY (Heterozygous condition): Two different sex chromosomes (X and Y) — normal human male. The organism is heterozygous at the sex-determining locus.
• XX (Homozygous condition): Two identical sex chromosomes (both X) — normal human female. The organism is homozygous at the sex locus.
• XO (Hemizygous condition): Only one X chromosome with no corresponding partner — Turner syndrome (45, XO). Hemizygous means having only one copy of a gene/chromosome instead of the usual two.

Turner Syndrome (from notes)

45 (44 + XO). Barr bodies = 0. Female phenotype but infertile.